Sensitive electrical relay



Aug. 21, 1951 B SENSITIVE ELECTRICAL RELAY 2 Sheets-Sheet 1 Filed June 29, 1945 a 0 Eli 2 Sheets-Sheet 2 A. H LAMB SENSITIVE ELECTRICAL RELAY Aug. 21, 1951 Filed June 29, 1945 a 1 4 a z Patented Aug. 21, 1951 UNITED STATES PATENT OFFICE SENSITIVE ELECTRICAL RELAY Application June 29, 1945, Serial No. 602,239

1 Claim. 1

This invention relates to sensitive electrical relays of the magnetic contact type, and more particularly to the mechanism for resetting the contacts after a closure thereof.

The contacts of relays such as described and claimed in my prior Patents 2,014,385 and 2,014,386 are held in engagement by a magnetic attraction that is substantially greater than the torque developed by the normal current flow through the relay coil, and various mechanical and electrical arrangements have been built into the relays or incorporated in the relay circuits to reset the magnetic contacts. The resetting mechanism of the present invention is of the mechanical type and may be operated manually or automatically by a solenoid that is energized by a closure of the relay contacts.

Objects of the invention are to provide magnetic contact relays having resetting mechanisms actuated by push buttons, either manually or automatically by solenoids. Other objects are to provide relays of the type stated in which the push buttons, and their actuating solenoids if the resetting mechanism is operated electrically, are mounted on the removable covers of the relay housings.

These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawings in which:

Fig. 1 is a front elevation of a relay embodying the invention;

Fig. 2 is a similar view of the same relay but provided with a solenoid operator for the resetting push button;

Fig. 3 is a fragmentary sectional view, on a larger scale, through a wall of the relay case on a plane through the push button assembly;

Fig. 4 is a front elevation of a double contact relay in which the resetting devices for both stationary contacts are actuated by a single push button that extends through the front wall of the relay casing;

Fig. 5 is a similar view of the relay but with the push button assembly and front wall of the case removed;

Fig. 6 is a transverse section as seen on the plane of section line 66 of Fig. 5;

Fig. '7 is a perspective view of the resetting levers; and

Fig. 8 is a front elevation of a double contact relay in which the resetting push button assembly is mounted on a side wall of the relay case.

In Figs. 1 and 2, the reference numeral l identifies the insulating material base which carries the entire relay mechanism except the resetting push button assembly 2 that is mounted on the casing 3, preferably of a transparent plastic as shown, that is secured to the base by screws 4. The relay includes the usual permanent magnet 5 that is secured to the base I, a bridge 6 mounted on the magnet and carrying the upper bearing for a moving system comprising a coil 1 and a pointer or contact arm 8 on which the soft iron rider 9 is secured. A scale plate In and a stationary contact I l are also supported on the magnet 5 in the usual manner, the contact arm 8 and contact ll being connected by leads, not shown, to relay terminals C and 1-1 respectively. The circuit connections to the moving coil 1 are made through terminals l2 mounted on the base I. As described in the prior patents, the pointer B is displaced angularly in accordance with minute currents in the moving coil 1, for example by currents of the order of a few microamperes, until the soft iron rider 9 enters the field of the magnetized contact H. The pointer is then drawn to the contact I I by a magnetic attraction and the contact rider 9 strikes the contact H with sufiicient force to break through any nonconducting films that may have formed on the cooperating contacts. The magnetic attraction provides good contact closures under pressures that are substantially in excess of the torque that can be developed by the moving coil 1. An outside force must be applied to the pointer 8 to separate the magnetic contact 9 from the stationary magnetic contact I I.

According to this invention, the outside force is applied through a push button assembly 2 that is mounted on the case 3 of the relay housing, see Fig. 3. The movable or active portion of this assembly comprises a plunger rod I3 having a button 14 threaded and/or cemented to its outer end and a small insulating material body [5 at its inner end for engagement with the pointer 8. For mounting the plunger rod l3, there is provided a small tubular housing l'l one end of which is reduced in cross-section to establish a shoulder abutting the inside face of casing 3 and also an elongated neck portion l6 which extends through an opening in the wall of casing 3. The neck portion I6 is threaded at its outer end to receive a nut l8 which when screwed down secures the housing rigidly to the casing 3. The neck portion [6 contains an axial bore forming a comparatively long sleeve bearingfor supporting the rod [3 which passes through it and also the main body portion of housing IT. The rod I3 is normally held in retracted position by a spring I9 within the housing ll, the spring seating between a disk secured to the rod 13 and a washer 2| that bears against the inturned inner end of the housing H.

The relay as illustrated in Fig. 1 is to be used with a circuit or apparatus that does not require an immediate resetting of the relay after a closure of the contacts 9, H. The operator may check the apparatus periodically to determine the condition of the relay, or the apparatus may include an alarm circuit that is energized by the relay. When the operator finds that the relay contacts 9, II have closed, he may push the button [4 at once or at some later time when resetting of the relay is in order.

Reverting to Fig. 2 which illustrates an automatic system for resetting the relay upon a closure of contacts 9, II, the solenoid 22 has an armature 23 with a bent arm 24 that extends back of the button I l and forces the same inwardly when the solenoid is energized. The solenoid is connected to the relay terminals C, H through a battery B or other current source, and is therefore energized by a closure of the relay contacts 9, H. The load may be in series circuit with the current source B and solenoid 22 or, as shown, the load circuit may be connected across contacts 25, 25' that are closed when the solenoid is energized.

In a double contact type of relay, as shown in Fig. 4, the soft iron rider 9 of contact arm 8 may be attracted to the high contact H or to the low contact II, and a single push button assemblyZ is mounted on the front wall of the transparent case 3 to separate the contact arm from either of the fixed contacts. The mechanical linkage for engaging the contact arm 8 to effect this separation includes a pair of bent levers 26, 26' supported on a bridge strap 21 for rocking movement on journal pins 28, 28' respectively that are located below and parallel to the zero center position of the contact arm 8. The upper ends of the levers 26, 26' are bent towards each other and then at right angles to provide extensions 29, 29' respectively that are normally just clear of the contact arm 8 when its rider 9 is seated on contacts II or II respectively. A spring 30 tends to hold the lever 26 in its inactive position, and the lower arm 3| of lever 26 extends under the lower arm 3| of lever 26' to retain that lever in inactive position. The end 32 of lever arm 31 is arranged directly beneath the insulating rod end [5 of the push button assembly 2, and depression of the push button rocks the upper ends of resetting levers 26, 26' towards each other to move the contact arm 8 towards its center position. The lever 26' is directly moved by the push button tip l5, and its arm 3|, forces the arm 31 of lever 26 downwardly to rock that lever. Upon f release of the push button, the spring 30 rocks the lever 26 back to inactive position, and it in desired. The side mounting may be convenient or desirable for manual operation in some installations but it is particularly advantageous for solenoid operation as it leaves the entire front of the relay case free from obstructions. The resetting levers 26, 26' may be identical with those previously described, the only difference in the resetting assembly being that the plunger tip I5 engages the upper bar of the lever 26' and not the lower end 32. The plunger may be actuated manually or by a resetting solenoid substantially like that shown in Fig. 2.

Combinations of manual and automatic reset are also possible in relays of the double contact type, for example a low contact could be added to a relay such as shown in Fig. 2, and a manu ally operated push button assembly could be mounted in the left hand wall of the case 3.

It is to be understood that the invention is not limited to the particular constructions herein shown and described as various modifications that may occur to those familiar with the design of sensitive relays fall within the scope of my invention as set forth in the following claim.

I claim:

In a relay of the magnetic contact type, the combination with a base, a relay supported exclusively by said base and comprising a perma nent magnet and pivoted coil, a contact arm secured to said coil and having a contact of magnetic material fixed thereto, a stationary contact of magnetic material supported from said base, one of said contacts being magnetized, and terminals for said coil and contacts supported on and accessible from the relay side of said base; of a case cooperating with said base to form a cover for said relay, a tubular housing disposed within said case and having an e1on gated neck portion extending through and secured to the Wall of said case, a pusher rod terminating at its outer end in a button adapted for manual actuation of the rod and at its inner end in a body of insulating material for direct engagement with said contact arm to separate it from said stationary contact upon inward sliding movement of the arm from an outward inactive position, said neck portion of said housing constituting a bearing sleeve for said pusher rod which extends therethrough from the exterior of saidcasing, and spring means within said housing cooperative with said pusher rod and yieldingly retaining said pusher rod in said outward inactive position.

ANTHONY I-I. LAMB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 

